Originally Posted by John St.Amant

I found that the plastic diff wasnt able to hold up durring hard acceleration and was slipping. Probably the same issue you had but when I took it out I noticed that the head of the diff screw was on the right hand side of the car. So upon replacing it with the metal diff I flipped it over so the diff screw head was on the left side rear like all my TRF 416. and I seem to have solved that issue... for now anyways. But usually when that happens theres a lubrication issue for the thrust bearing. Make sure that those little balls get enough grease and are moving free and easy .